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Discussion Starter · #1 ·
I have a 85 C10 with a 350. My stock oil pressure gauge stopped working.I replaced the oil gauge and a oil sending unit as well. I noticed while changing the sending unit there is another one on the same brass fitting that is located under the distributor. Now the gauge pegs to "0" when the key is on then when the engine is running it pegs to "60". This truck came with a 305 and then swapped out with a 350 before I became the owner. I noticed on info around the internet the pressure unit others have is a Bell looking style unit. Is that what really belongs to it? And the other switch which is on the brass fitting too, should it be replaced too? I could put a aftermarket oil pressure gauge on it but I rather not. I would like to keep it somewhat stock. Any help would be great!!Thanks
 

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Morely how high is the reading on the gauge just looking at it without running 0 to 60....? Does your connections look like this..image....? The one visible (with 2 connectors) is to activate the choke heater . The harness connector is a snap-fit. This switch will also illuminate the "choke" light on the cluster when the key is in the ON position. IT DOES NOT DRIVE THE OIL PRESSURE GAUGE.
It will extinguish the choke light when oil pressure is established. Also acts as an idiot light - if the "choke" light comes on while driving - shut down. You may have lost oil pressure.
 

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I would guess you got the wrong sending unit, or a bad one.
Charlie, I`m thinking type of oil and or cold, he may peg the gauge, if it only reads to 60 lbs the possibility is there, he won`t know til the operating temp levels it off at idle....! The other issue is is he has a transplant, we don`t know what the oil pressure relief spring is set at...!
 

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A question I should have asked before. Dose it peg to 60 just turning on the ignition? or when you start it and what is the highest the gauge reads. Could be shorted wire??? Was the gauge working when you got the truck if so what was the pressure then??
 

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Discussion Starter · #6 ·
Thank you for the reply. My sending units look like the one on the right with the multiple wires on to the connector. The one on the left I do not have. It is shaped and looks exactly like the one on the right with multiple wires. But it only has one wire connecting to it.Before actually starting it the needle on the gauge is in the middle. Once the key is turned on it drops to zero. Then after the engine is running it stays on the 60 mark. It did work when I bought the truck.While running it stayed around 20-30. I have oil in the truck as well as having no leaks. It does not burn oil either. In fact it runs very strong and smooth.Should I change out the sending unit to the Bell Style shown in your image?Thanks
 

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Discussion Starter · #9 ·
Its Fixed!

Thanks to all for the suggestions. I took the advice of changing out the unit. It works like a champ. Thanks again!
 

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Choke Light

Morely how high is the reading on the gauge just looking at it without running 0 to 60....? Does your connections look like this..image....? The one visible (with 2 connectors) is to activate the choke heater . The harness connector is a snap-fit. This switch will also illuminate the "choke" light on the cluster when the key is in the ON position. IT DOES NOT DRIVE THE OIL PRESSURE GAUGE.
It will extinguish the choke light when oil pressure is established. Also acts as an idiot light - if the "choke" light comes on while driving - shut down. You may have lost oil pressure.
This is an old thread but states my problem. Some times after driving for 30-40 minutes the choke light come on with the oil pressure gage shows good pressure. When I stop and check oil(always good) the choke light goes out when I restart. Could this be an electrical glitch or do I have a real problem?
 

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This is an old thread but states my problem. Some times after driving for 30-40 minutes the choke light come on with the oil pressure gage shows good pressure. When I stop and check oil(always good) the choke light goes out when I restart. Could this be an electrical glitch or do I have a real problem?
If its just the choke light, then I would say replace the switch...
 

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My new-to-me truck has a transplanted 350 Vortec, and the oil pressure gauge is pegged to about 90% when it’s running > 2200 RPM or so. Is this normal? What’s the best approach to verify this and fix? This is all new to me.
 

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My new-to-me truck has a transplanted 350 Vortec, and the oil pressure gauge is pegged to about 90% when it’s running > 2200 RPM or so. Is this normal? What’s the best approach to verify this and fix? This is all new to me.
Quit Depends on what engine you have also. The earlier motors with 2 piece rear main run lower pressure than later 1 piece rear mains. So if it was a nice new crate engine, it may be a 1 piece rear main and have higher pressure.
The earlier gauges from `68 to `72 were not all that accurate as well, you may even want to install a good oil pressure gauge under hood to verify oil pressure..there are other factors as well as the engine plants set oil pressure relief spring to 65 pounds pressure at 3000 rpm...
 

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Quit Depends on what engine you have also. The earlier motors with 2 piece rear main run lower pressure than later 1 piece rear mains. So if it was a nice new crate engine, it may be a 1 piece rear main and have higher pressure.
Its not a new crate engine I am sure. I do need to check details on this motor however, and I was looking at this robust reference here to do so --> http://www.nastyz28.com/sbchevy/sblock.html

The earlier gauges from `68 to `72 were not all that accurate as well, you may even want to install a good oil pressure gauge under hood to verify oil pressure..there are other factors as well as the engine plants set oil pressure relief spring to 65 pounds pressure at 3000 rpm...
I was thinking this exact thing - a gauge for both the oil pressure and fuel line pressure (electric fuel pump) under the hood.

-quig
 

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Quit, you`ll need the suffix code from the engine, front passenger side just below the head, that give us pretty much what we need.
 

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Couldn't find a code on the front passenger side, but managed to snap a picture of the casting code on the rear of the engine with my phone. Its 10243880, which according to several references is a late 90's 350 crate engine AND ZZ4 (not sure which, but I guess they are the same).
 

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Quiq take this post above to the unit year section, that way everyone will see it..
 
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